The Luftwaffe was much better prepared for the task of air-sea rescue than the RAF, with one unit, the Seenotdienst equipped with Heinkel He 59 floatplanes, specifically tasked with picking up downed aircrew from the North Sea, English Channel and the Dover Straits. In addition, Luftwaffe aircraft were equipped with life rafts and the aircrew were provided with sachets of a chemical called fluorescein which, on reacting with water, created a large, easy-to-see, bright green patch.

One of the most controversial orders was issued to the RAF on 13 July; this stated that as of 20 July, Seenotdienst aircraft were to be shot down. One of the reasons given by Churchill was:

We did not recognise this means of rescuing enemy pilots so they could come and bomb our civil population again... all German air ambulances were forced down or shot down by our fighters on definite orders approved by the War Cabinet.

On 1 July, an He 59 searching for a Luftwaffe crew was forced to alight on the sea after sustaining damage in an attack by 72 Squadron.On 9 July, Flt Lt Alan Deere was leading a flight of 54 Squadron Spitfires when they were vectored to unidentified air activity off the coast near Deal, Kent. The flight spotted an aircraft flying at wavetop height:

It was a seaplane painted silver, and from a distance there appeared to be civilian registration letters painted on the upper surface of the wing. I was wondering what to do about this unexpected discovery when Johnny burst through on the R/T. "Red Leader there are about a dozen 109s flying in loose formation, well behind and slightly above the seaplane.

Soon after "Red Flight" of 54 Squadron engaged the Bf 109s while "Yellow Flight" attacked the seaplane, which landed on the water with a dead engine. On further investigation, it was found that the crew of the He 59 had been radioing information on the movement of British shipping back to headquarters. Questions were also raised as to why an aircraft operating in a "peaceful" role needed a large fighter escort. These events resulted in the Air Ministry issuing a communique to the German government on 14 July:

It has come to the notice of His Majesty's Government in the United Kingdom that enemy aircraft in civilian markings and marked with the red cross have recently flown over British Ships at sea and in the vicinity of the British coast, and that they are being employed for purposes which His Majesty's Government cannot regard as being consistent with the privileges generally accorded to the Red Cross.

His Majesty's Government desire to accord to ambulance aircraft reasonable facilities for the transportation of the sick and wounded, in accordance with Red Cross Convention, and aircraft engaged in the direct evacuation of sick and wounded will be respected, provided that they comply with the relevant provisions of the Geneva Convention (italics added)

His Majesty's Government are unable, however, to grant immunity to such aircraft flying over areas in which operations are in progress on land or at sea, or approaching British or Allied territory, or territory in British occupation, or British or Allied ships.

Ambulance aircraft which do not comply with the above will do so at their own risk and peril.

As a result of this and other encounters with RAF fighters, the white He 59s were repainted in camouflage colours and armed with defensive machine guns. Although another four He 59s were shot down by RAF aircraft, the Seenotdienst continued to pick up downed Luftwaffe and Allied aircrew throughout the battle, earning praise from Adolph Galland for their gallantry.